Studies in Glacier Physics on the Penny Ice Cap, Baffin Island, 1953: Part III: Seismic Sounding

Abstract

Firn and ice thickness measurements were carried out by seismic refraction and reflection methods on a flat col of the highland snowfields of the Penny Ice Cap and on a medium-sized valley glacier (Highway Glacier). The longitudinal wave velocities were found to vary from some 1000 m./sec. (3280 ft./sec.) in firn to 3810 m.,/sec. (12,500 ft./sec.) in ice and approximately 6000 m.% sec. (20,000 ft./sec.) in the bedrock (gneiss). The thickness of firn and ice at the firn col was found to be 254 m. (834 ft.). On Highway Glacier some 80 reflections were evaluated, giving position, dip and strike of the bedrock surface. A longitudinal profile of Highway Glacier from the junction of three main tributary glaciers to the tongue is given; the ice thickness slowly decreases. At the junction, the bedrock is 400 m. (1310 ft.) deep, there is no deep basin as might be expected from the surface features. The mean slope of the glacier surface is about 3° of arc and of the bed about 1°.